Supplying a from-end of true matters only when the count is provided; in that case only the rightmost count elements satisfying the test are deleted.

Count, if supplied, limits the number of elements removed or deleted; if more than count elements satisfy the test, then of these elements only the leftmost or rightmost, depending on from-end, are deleted or removed, as many as specified by count. If count is supplied and negative, the behavior is as if zero had been supplied instead. If count is nil, all matching items are affected.

For all these functions, elements not removed or deleted occur in the same order in the result as they did in sequence.

remove, remove-if, remove-if-not return a sequence of the same type as sequence that has the same elements except that those in the subsequence bounded by start and end and satisfying the test have been removed. This is a non-destructive operation. If any elements need to be removed, the result will be a copy. The result of remove may share with sequence; the result may be identical to the input sequence if no elements need to be removed.

delete, delete-if, and delete-if-not return a sequence of the same type as sequence that has the same elements except that those in the subsequence bounded by start and end and satisfying the test have been deleted. Sequence may be destroyed and used to construct the result; however, the result might or might not be identical to sequence.

delete, when sequence is a list, is permitted to setf any part, car or cdr, of the top-level list structure in that sequence. When sequence is a vector, delete is permitted to change the dimensions of the vector and to slide its elements into new positions without permuting them to produce the resulting vector.